Preheat oven to 425°F. In a mixing bowl, toss blood orange slices and scallions with 1/2 tbsp olive oil and salt and pepper to taste. Lay the sliced oranges and scallions evenly on a baking sheet lined with parchment paper, drizzling with any remaining oil from the mixing bowl.

Roast for 10-15 minutes, shaking the pan every five minutes to make sure the oranges don't burn.

Remove from oven and let cool for at least 5 minutes.

While the oranges and scallions are roasting, combine the red onion and lemon juice in a bowl and let sit for 5 minutes, allowing onion to soften.